Percutaneous irreversible electroporation of surgically unresectable pancreatic cancer: a case report

Margin Accentuation Irreversible Electroporation in Stage III Pancreatic Cancer: A Systematic Review

Simple Summary

This literature review shows preliminary evidence to suggest that electroporation, the use of electricity to cause the death of cells around the tumour, may be associated with an improved survival and complete resection rates following pancreatic surgery for higher stage pancreatic cancer. However, one in five patients have a complication from the procedure that alters their normal course in hospital. Moreover, the number of patients who underwent this technique is small and further data is needed to support the preliminary evidence. The results therefore should be interpreted with caution.

Abstract

The present systematic review aimed to summarise the available evidence on indications and oncological outcomes after MA IRE for stage III pancreatic cancer (PC). A literature search was performed in the Pubmed, MEDLINE, EMBASE, SCOPUS databases using the PRISMA framework to identify all MA IRE studies. Nine studies with 235 locally advanced (LA) (82%, 192/235) or Borderline resectable (BR) PC (18%, 43/235) patients undergoing MA IRE pancreatic resection were included. Patients were mostly male (56%) with a weighted-mean age of 61 years (95% CI: 58–64). Pancreatoduodenectomy was performed in 51% (120/235) and distal pancreatectomy in 49% (115/235). R0 resection rate was 73% (77/105). Clavien Dindo grade 3–5 postoperative complications occurred in 19% (36/187). Follow-up intervals ranged from 3 to 29 months. Local and systematic recurrences were noted in 8 and 43 patients, respectively. The weighted-mean progression free survival was 11 months (95% CI: 7–15). The weighted-mean overall survival was 22 months (95% CI 20–23 months) and 8 months (95% CI 1–32 months) for MA IRE and IRE alone, respectively. Early non-randomised data suggest MA IRE during pancreatic surgery for stage III pancreatic cancer may result in increased R0 resection rates and improved OS with acceptable postoperative morbidity. Further, larger studies are warranted to corroborate this evidence.

Effect of input voltage frequency on the distribution of electrical stresses on the cell surface based on single-cell dielectrophoresis analysis

Electroporation is defined as cell membrane permeabilization under the application of electric fields. The mechanism of hydrophilic pore formation is not yet well understood. When cells are exposed to electric fields, electrical stresses act on their surfaces. These electrical stresses play a crucial role in cell membrane structural changes, which lead to cell permeabilization. These electrical stresses depend on the dielectric properties of the cell, buffer solution, and the applied electric field characteristics. In the current study, the effect of electric field frequency on the electrical stresses distribution on the cell surface and cell deformation is numerically and experimentally investigated. As previous studies were mostly focused on the effect of electric fields on a group of cells, the present study focused on the behavior of a single cell exposed to an electric field. To accomplish this, the effect of cells on electrostatic potential distribution and electric field must be considered. To do this, Fast immersed interface method (IIM) was used to discretize the governing quasi-electrostatic equations. Numerical results confirmed the accuracy of fast IIM in satisfying the internal electrical boundary conditions on the cell surface. Finally, experimental results showed the effect of applied electric field on cell deformation at different frequencies.

Irreversible electroporation and adjuvant chemoradiotherapy for locally advanced pancreatic carcinoma

CONTEXT

The safety and efficacy of irreversible electroporation (IRE) for locally advanced pancreatic carcinoma (LAPC) are well established. However, whether adjuvant chemoradiotherapy after IRE increases, the survival rate remains unknown. Therefore, this study evaluated the effect of chemoradiotherapy combined with IRE in patients with LAPC.

SUBJECTS AND METHODS

We retrospectively analyzed 42 patients with LAPC between July 2015 and December 2016 at PLA General Hospital treated with IRE or IRE combined with radiation and/or chemotherapy. These patients were divided into the IRE group and the combined-therapy group. All patients underwent computed tomography (CT), magnetic resonance imaging, and positron-emission tomography-CT and no signs of metastases were found. The prognosis of these patients was observed.

RESULTS

The times after operation and after diagnosis in the combined-therapy group (304.20 ± 118.54) and (334.40 ± 114.07) days, respectively, were better those than in the IRE group (214.36 ± 95.68) and (244.68 ± 110.61) days, respectively. Moreover, patients in the combined-therapy group had a significantly better survival rate than the IRE group (80 vs. 45.45%, P < 0.05).

CONCLUSIONS

IRE combined with radiotherapy or chemotherapy was superior to IRE alone for the treatment of LAPC, as it prolonged the survival time and improved the survival rate, making it worthy of wide dissemination and clinical application.

Real-time prediction of patient immune cell modulation during irreversible electroporation therapy

Immunotherapies have demonstrated limited efficacy in pancreatic ductal adenocarcinoma (PDAC) patients despite their success in treating other tumor types. This limitation is largely due to the relatively immunosuppressive environment surrounding the tumor. A focal ablative technique called irreversible electroporation (IRE) has been shown to modulate this environment, enhancing the efficacy of immunotherapy. One enhancing factor related to improved prognosis is a decrease in regulatory T cells (T_reg). This decrease has been previously unpredictable for clinicians using IRE, who currently have limited real-time metrics for determining the activation of the patient’s immune response. Here, we report that larger overall changes in output current are correlated with larger decreases in T cell populations 24 hours post-treatment. This result suggests that clinicians can make real-time decisions regarding optimal follow-up therapy based on the range of output current delivered during treatment. This capability could maximize the immunomodulating effect of IRE in synergy with follow-up immunotherapy. Additionally, these results suggest that feedback from a preliminary IRE treatment of the local tumor may help inform clinicians regarding the timing and choice of subsequent therapies, such as resection, immunotherapy, chemotherapy, or follow-up thermal or non-thermal ablation.

A prospective, multi-institution assessment of irreversible electroporation for treatment of locally advanced pancreatic adenocarcinoma: initial outcomes from the AHPBA pancreatic registry

BACKGROUND

The optimal treatment and management of locally advanced pancreatic cancer (LAPC) remains unclear and controversial. This study aimed to report the initial outcomes of the AHPBA Registry and evaluate the reproducibility of existing evidence that the addition of Irreversible Electroporation (IRE), a nonthermal ablative treatment, confers survival benefits beyond standard therapeutic options for patients with LAPC.

METHODS

From December 2015 to October 2017, patients with LAPC were treated with open-technique IRE following the AHPBA Registry Protocols. Patient demographics, long-term outcomes, and adverse events were recorded. Survival analyses were performed using Kaplan-Meier (KM) curves for overall survival (OS), progression free survival (PFS) and time to progression (TTP).

RESULTS

A total of 152 patients underwent successful IRE. Morbidity and mortality were 18% and 2% respectively, with 19 (13%) patients experiencing severe adverse events. Nine (6%) patients presented with local recurrence. Median TTP, PFS, and OS from diagnosis were 27.3 months, 22.8 months, and 30.7 months respectively.

CONCLUSION

The combination of IRE with established multiagent therapy is safe and demonstrates encouraging survival among patients with LAPC. IRE is associated with a low rate of serious adverse events and has been optimized for more widespread adoption through the standardized protocols available through the AHPBA registry.

Locally Advanced Pancreatic Cancer: Work-Up, Staging, and Local Intervention Strategies

Locally advanced pancreatic cancer (LAPC) has several definitions but essentially is a nonmetastasized pancreatic cancer, in which upfront resection is considered not beneficial due to extensive vascular involvement and consequent high chance of a nonradical resection. The introduction of FOLFIRINOX chemotherapy and gemcitabine-nab-paclitaxel (gem-nab) has had major implications for the management and outcome of patients with LAPC. After 4-6 months induction chemotherapy, the majority of patients have stable disease or even tumor-regression. Of these, 12 to 35% are successfully downstaged to resectable disease. Several studies have reported a 30-35 months overall survival after resection; although it currently remains unclear if this is a result of the resection or the good response to chemotherapy. Following chemotherapy, selection of patients for resection is difficult, as contrast-enhanced computed-tomography (CT) scan is unreliable in differentiating between viable tumor and fibrosis. In case a resection is not considered possible but stable disease is observed, local ablative techniques are being studied, such as irreversible electroporation, radiofrequency ablation, and stereotactic body radiation therapy. Pragmatic, multicenter, randomized studies will ultimately have to confirm the exact role of both surgical exploration and ablation in these patients. Since evidence-based guidelines for the management of LAPC are lacking, this review proposes a standardized approach for the treatment of LAPC based on the best available evidence.

Systematic Review of Surgical and Percutaneous Irreversible Electroporation in the Treatment of Locally Advanced Pancreatic Cancer

OBJECTIVE

The aim of the present systematic review was to collect, analyze, and critically evaluate the role of irreversible electroporation (IRE) in locally advanced pancreatic cancer (LAPC). Furthermore, we sought to analyze the different approaches of IRE (open, laparoscopic, and percutaneous) and assess the relative outcomes.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Using the MEDLINE (1966-2018), Scopus (2004-2018), Google Scholar (2004-2018) and ClinicalTrials.gov databases, eligible articles published up to August 2018 were included. The following keywords were applied: 'irreversible electroporation', 'IRE', 'LAPC', 'unresectable pancreatic cancer', 'palliative treatment', 'locally advanced pancreatic cancer', 'ablation' and 'ablative treatment'.

RESULTS

IRE for LAPC was feasible and safe; however, it was associated with morbidity in approximately one in three patients, some of whom experienced serious complications, particularly after surgical IRE. In addition, while mortality following IRE was uncommon, it did occur in 2% of patients. While some studies suggested a survival benefit, others failed to note an improvement in long-term outcomes following IRE compared with other therapies.

CONCLUSIONS

Providers and patients need to be aware of the potential morbidity and mortality associated with IRE. In addition, based on the literature to date, the survival benefit of IRE for LAPC remains to be elucidated. Conclusive and definitive evidence to support a survival benefit of IRE does not currently exist. Future multicenter, randomized, prospective trials are needed to clarify the role of IRE in patients with LAPC.

Percutaneous irreversible electroporation with systemic treatment for locally advanced pancreatic adenocarcinoma

Background

The prognosis for unresectable locally advanced pancreatic adenocarcinoma (LAPC) remains poor. There is increasing interest in modern ablative techniques to improve outcomes. We report on the potential value of integrating percutaneous irreversible electroporation (IRE) in patients undergoing systemic chemotherapy.

Methods

Seventy-five patients with unresectable pancreatic carcinoma underwent percutaneous IRE after chemotherapy using computerised tomography guidance under general anaesthesia. Postoperative immediate and 30-day morbidity and mortality, progression-free (PFS) and overall survival (OS) were evaluated.

Results

Post-procedural immediate and 30-day mortality rates were both zero. All-grade adverse events were 25%. Median in-patient stay was 1 day (range, 1-5 days). Median OS and PFS post-IRE for LAPC were 27 and 15 months respectively. Four patients with LAPC down-staged post-IRE ablation to be surgically resectable, with R0 resections in 3 cases.

Conclusions

These results suggest that percutaneous IRE ablation of unresectable LAPC is safe to integrate with standard-of-care chemotherapy and may improve survival, which provides a template for further evaluation in prospective randomized clinical trials.

Technology of irreversible electroporation and review of its clinical data on liver cancers

INTRODUCTION

Irreversible electroporation (IRE) has developed as a novel percutaneous ablative technique over the past decade and its utility in the treatment of primary and metastatic liver disease has progressed rapidly.

AREAS COVERED

After discussing the principles behind the technology and the practical steps in its use, this article offers a detailed analysis of the recent published work that evaluates its safety and efficacy. The strengths and weaknesses of other ablative techniques, including radiofrequency ablation, microwave ablation and cryoablation, are discussed in detail. Other aspects of IRE, including post-treatment clinical follow-up, expected imaging findings, and the most frequently encountered complications, are covered. Finally, the future of IRE is examined as it pertains to advancements in the treatment of hepatic malignancy.

EXPERT COMMENTARY

The characteristics of IRE that make this technology uniquely suited for the treatment of liver tumors have allowed it to gain a significant foothold in interventional oncology. Continued development of IRE will lead to further advances in the management of previously untreatable liver cancers.

Ablative Therapies for Locally Advanced Pancreatic Cancer

The vast majority of patients who present with pancreatic adenocarcinoma have locally advanced or metastatic disease at the time of presentation without possibility of cure. Although in recent years there have been some new promising chemotherapy regimens that improve overall survival by a few months, the prognosis remains dismal. There is, however, a subset of patients who experience durable stable disease or partial responses after initial courses of chemotherapy with locally advanced disease. In these select patients, there remains interest in local ablative therapy with or without resection as a means for local control, palliation of symptoms, and possible improved survival. This review describes the techniques, complications, and expected benefits of several ablative techniques as a treatment modality for locally advanced pancreatic cancer.

Multi-modality imaging-monitored creation of rat orthotopic pancreatic head cancer with obstructive jaundice

Purpose

To investigate the feasibility of using multi-modality imaging to monitor the creation of rat models with orthotopic pancreatic head cancer with obstructive jaundice.

Results

27 of 52 rats (51.92%) developed pancreatic head cancer. The tumor formation rate was significantly higher in the animal group receiving bioluminescent tumor, compared to the group receiving non-bioluminescent donor tumors [78.1% (25/32 rats) vs 10.0% (2/20 rats), P = 0.0001]. Both ultrasound imaging and MRI clearly characterized the orthotopic tumors. Laboratory biochemistry test for those rats with obstructive jaundice showed elevated levels of bilirubin, aspartate transaminase (AST), alkaline phosphatase (ALT) and gamma-glutamyl transpeptidase (λ-GGT), compared with those rats without jaundice (P < 0.05). Correlative pathology confirmed that all tumors were ductal adenocarcinomas, and located in pancreatic head regions.

Materials and Methods

Rat pancreatic adenocarcinoma cells (DSL-6A/C1) were first transfected with lentivirus/mCherry-luciferase genes, and then subcutaneously implanted into flanks of donor immunocompetent Lewis rats, to create pancreatic tumor tissues. The tumor tissues from donor rats with either bioluminescence signal or without the signal were then transplanted into the pancreatic heads of 52 recipient Lewis rats. Bioluminescence optical and ultrasound imaging, as well as magnetic resonance imaging (MRI), were performed to follow up the tumor formation and growth in these tumor-transplanted rats. Physical examination and biochemistry test were used to discern the rats with obstructive jaundice. The rats were euthanized for subsequent histologic correlation and confirmation.

Conclusions

We successfully created a new rat model with orthotopic pancreatic head cancer, which can be accurately monitored and visualized by different imaging modalities.

Arterial complication of irreversible electroporation procedure for locally advanced pancreatic cancer

Irreversible electroporation (IRE) is a non-thermal ablation technique used especially in locally advanced pancreatic carcinomas that are considered surgically unresectable. We present the first case of acute superior mesenteric artery (SMA) occlusion secondary to pancreatic IRE procedure that has not been reported before in the literature. A 66-year-old man underwent neoadjuvant chemoradiotherapy for locally advanced pancreatic ductal adenocarcinoma. IRE procedure was applied to the patient during laparotomy under general anesthesia. After finishing the procedure, an acute intestinal ischemia was detected. A conventional vascular angiography was performed and a metallic stent was successfully placed to the SMA and blood flow was maintained. It is important to be careful in such cases of tumor involvement of SMA when evaluating for IRE procedure of pancreatic tumor.

Irreversible electroporation in locally advanced pancreatic cancer: A call for standardization of energy delivery

Irreversible Electroporation (IRE) is used to treat locally advanced cancers, commonly of the pancreas, liver, kidney, and other soft tissues. Precise eligibility for IRE should be established in each individual patient by a multidisciplinary team based on comprehensive clinical, imaging, and laboratory assessment. Standardization of IRE technique and protocols is expected to improve safety, lead to reproducible outcomes, and facilitate further research into IRE. The present article provides a set of technical recommendations for the use of IRE in the treatment of locally advanced pancreatic cancer. J. Surg. Oncol. 2016;114:865-871. © 2016 2016 Wiley Periodicals, Inc.

Histological and Mathematical Analysis of the Irreversibly Electroporated Liver Tissue

Irreversible electroporation has clinically been used to treat various types of cancer. A plan on how to apply irreversible electroporation before practicing is very important to increase the ablation area and reduce the side effects. Several electrical models have been developed to predict the ablation area with applied electric energy. In this experiment, the static relationship between applied electric energy and ablated area was mathematically and experimentally investigated at 10 hours after applying irreversible electroporation. We performed the irreversible electroporation on the liver tissue of Sprague Dawley rats (male, 8 weeks, weighing 250-350 g). The ablated area was measured based on histological analysis and compared with the mathematical calculation from the electric energy, assuming that the tissue is homogeneous. The ablated area increased with the increase in applied electric energy. The numerically calculated contour lines of electric energy density overlapped well with the apoptotic area induced by the irreversible electroporation. The overlapped area clearly showed that the destructive threshold of apoptosis between electrodes is electric energy density level of 5.9 × 10⁵ J/m³. The results of the present study suggested that the clinical results of the irreversible electroporation on a liver tissue could be predicted through mathematical calculation.

Electrochemotherapy in pancreatic adenocarcinoma treatment: pre-clinical and clinical studies

Background

Pancreatic adenocarcinoma is currently one of the deadliest cancers with high mortality rate. This disease leads to an aggressive local invasion and early metastases, and is poorly responsive to treatment with chemotherapy or chemo-radiotherapy. Radical resection is still the only curative treatment for pancreatic cancer, but it is generally accepted that a multimodality strategy is necessary for its management. Therefore, new alternative therapies have been considered for local treatment.

Conclusions

Chemotherapeutic resistance in pancreatic cancer is associated to a low penetration of drugs into tumour cells due to the presence of fibrotic stroma surrounding cells. In order to increase the uptake of chemotherapeutic drugs into tumour cells, electrochemotherapy can be used for treatment of pancreatic adenocarcinoma leading to an increased tumour response rate. This review will summarize the published papers reported in literature on the efficacy and safety of electrochemotherapy in pre-clinical and clinical studies on pancreatic cancer.

Local Ablative Strategies for Ductal Pancreatic Cancer (Radiofrequency Ablation, Irreversible Electroporation): A Review

Pancreatic ductal adenocarcinoma (PDAC) has still a dismal prognosis. Locally advanced pancreatic cancer (LAPC) accounts for the 40% of the new diagnoses. Current treatment options are based on chemo- and radiotherapy regimens. Local ablative techniques seem to be the future therapeutic option for stage-III patients with PDAC. Radiofrequency Ablation (RFA) and Irreversible Electroporation (IRE) are actually the most emerging local ablative techniques used on LAPC. Initial clinical studies on the use of these techniques have already demonstrated encouraging results in terms of safety and feasibility. Unfortunately, few studies on their efficacy are currently available. Even though some reports on the overall survival are encouraging, randomized studies are still required to corroborate these findings. This study provides an up-to-date overview and a thematic summary of the current available evidence on the application of RFA and IRE on PDAC, together with a comparison of the two procedures.

Application of nanoknife ablation in unresectable pancreatic carcinoma: Present situation and prospects

Pancreatic cancer is a common malignant tumor of the digestive system with rapid progression and poor prognosis. The pathogenesis of pancreatic cancer is still unclear. Its incidence of is significantly rising, ranking fourth among all malignant tumors. Up to now, main therapeutic methods for pancreatic cancer contain surgical treatment, local ablation therapy, local radiotherapy, systemic chemotherapy, molecular targeted therapy, biological treatment and so on. Surgical treatment is still the only way to cure pancreatic cancer. However, most cases of pancreatic cancer are diagnosed at advanced stages, and only 20% of patients have a resectable disease. With the development of medical technology, nanoknife ablation, which is based on irreversible electroporation (IRE), has already come into people's vision. Both animal experiments and clinical studies have showed promising results. In this paper, we will discuss the present situation and prospects of application of nanometer knife ablation in the treatment of unresectable pancreatic carcinoma.

CT Findings of Patients Treated with Irreversible Electroporation for Locally Advanced Pancreatic Cancer

Introduction. In patients with locally advanced pancreatic cancer (LAPC), IRE has been shown to be safe for local disease control and palliation. As IRE continues to gain acceptance it is important to characterize the expected imaging findings. Materials and Methods. A review of our prospective soft tissue ablation registry from July 2010 to June 2013 was performed on patients who had undergone IRE for LAPC. Five masses treated with intraoperative IRE ablation for pancreatic tumors that underwent CT imaging before and after ablation were reviewed. Results and Discussion. Following IRE, the postablation bed is larger than the original ablated tumor. This ablation zone may get smaller in size (due to decreased edema and hyperemia) in the following months and more importantly remains stable provided there is no recurrence. In cases of recurrent disease there is increased size of the ablation bed, mass effect, and new or worsening vascular encasement or occlusion. Conclusion. CT imaging remains the best current imaging modality to assess post-IRE ablation changes. Serial imaging over at least 2-6 months must be employed to detect recurrence by comparing with prior studies in conjunction with clinical and serum studies. Larger imaging studies are underway to evaluate a more ideal imaging modality for this unique patient population.

Treatment of 200 locally advanced (stage III) pancreatic adenocarcinoma patients with irreversible electroporation: safety and efficacy

OBJECTIVES

Ablative therapies have been increasingly utilized in the treatment of locally advanced pancreatic cancer (LAPC). Irreversible electroporation (IRE) is an energy delivery system, effective in ablating tumors by inducing irreversible membrane destruction of cells. We aimed to demonstrate efficacy of treatment with IRE as part of multimodal treatment of LAPC.

METHODS

From July 2010 to October 2014, patients with radiographic stage III LAPC were treated with IRE and monitored under a multicenter, prospective institutional review board-approved registry. Perioperative 90-day outcomes, local failure, and overall survival were recorded.

RESULTS

A total of 200 patients with LAPC underwent IRE alone (n = 150) or pancreatic resection plus IRE for margin enhancement (n = 50). All patients underwent induction chemotherapy, and 52% received chemoradiation therapy as well for a median of 6 months (range, 5-13 months) before IRE. IRE was successfully performed in all patients. Thirty-seven percent of patients sustained complications, with a median grade of 2 (range, 1-5). Median length of stay was 6 days (range, 4-36 days). With a median follow-up of 29 months, 6 patients (3%) have experienced local recurrence. Median overall survival was 24.9 months (range: 4.9-85 months).

CONCLUSIONS

For patients with LAPC (stage III), the addition of IRE to conventional chemotherapy and radiation therapy results in substantially prolonged survival compared with historical controls. These results suggest that ablative control of the primary tumor may prolong survival.

Irreversible electroporation and the pancreas: What we know and where we are going?

Pancreatic adenocarcinoma continues to have a poor prognosis with 1 and 5 years survival rates of 27% and 6% respectively. The gold standard of treatment is resection, however, only approximately 10% of patients present with resectable disease. Approximately 40% of patients present with disease that is too locally advanced to resect. There is great interest in improving outcomes in this patient population and ablation techniques have been investigated as a potential solution. Unfortunately early investigations into thermal ablation techniques, particularly radiofrequency ablation, resulted in unacceptably high morbidity rates. Irreversible electroporation (IRE) has been introduced and is promising as it does not rely on thermal energy and has shown an ability to leave structural cells such as blood vessels and bile ducts intact during animal studies. IRE also does not suffer from heat sink effect, a concern given the large number of blood vessels surrounding the pancreas. IRE showed significant promise during preclinical animal trials and as such has moved on to clinical testing. There are as of yet only a few studies which look at the applications of IRE within humans in the setting of pancreatic adenocarcinoma. This paper reviews the basic principles, techniques, and current clinical data available on IRE.

Use of irreversible electroporation in unresectable pancreatic cancer

Irreversible electroporation is a non-thermal injury ablative modality that has been in clinical use since 2008 in the treatment of locally advanced soft tissue tumors. It has been reported to be utilized intraoperatively, laparoscopically or percutaneously. The method of action of IRE relies on a high voltage (maximum 3,000 volts) small microsecond pulse lengths (70 to 90 microseconds) to induce cell membrane porosity which leads to slow/protracted cell death over time. One of the largest unmet needs in oncology that IRE has been utilized is in locally advanced (stage III) pancreatic cancer. Recent studies have demonstrated the safety and palliation with encouraging improvement in overall survival. Its inherent limitation still remains tissue heterogeneity and the unique settings based on tumor histology and prior induction therapy. There remains a high technical demand of the end-user and the more extensive knowledge transfer which makes the learning curve longer in order to achieve appropriate and safe utilization.

Pancreatic Adenocarcinoma Treated With Irreversible Electroporation Case Report: First Experience and Outcome

Irreversible electroporation (IRE) is a new nonthermal tumor ablation modality that induces apoptosis in the treated tissue without affecting collagen. Its use is particularly indicated for tumors involving major structures, such as encompassed or infiltrated vessels and/or ducts, which need to be preserved and hinder or preclude surgical resection. We report a 66-year-old male patient with locally advanced pancreatic adenocarcinoma, treated with IRE.Two cycles of neoadjuvant chemotherapy with nab-paclitaxel and gemcitabine were administered. After these 2 cycles, IRE ablation was performed with a percutaneous transgastric access under general anesthesia. Later, 4 additional chemotherapy cycles were administrated. At 48 hours of electroporation, blood tests were normal. On day 5, a computed tomography (CT) scan showed portal vein and celiac artery were normal in appearance. Three months later, a positron emission tomography (PET) scan showed disappearance of abnormal uptake in the pancreas and other sites. A 12-month follow-up the patient is disease free.IRE opens a new way to treat tumors with involvement or proximity of neighboring structures. This procedure is more costly than other techniques and is not free of complications. The percutaneous transgastric access is feasible and without serious complications. In our case, complications were resolved and the patient presented a good short/medium-term outcome.

Irreversible electroporation of the pancreas is feasible and safe in a porcine survival model

OBJECTIVES

Use of thermal tumor ablation in the pancreatic parenchyma is limited because of the risk of pancreatitis, pancreatic fistula, or hemorrhage. This study aimed to evaluate the feasibility and safety of irreversible electroporation (IRE) in a porcine model.

METHODS

Ten pigs were divided into 2 study groups. In the first group, animals received IRE of the pancreatic tail and were killed after 60 minutes. In the second group, animals received IRE at the head of the pancreas and were followed up for 7 days. Clinical parameters, computed tomography imaging, laboratory results, and histology were obtained.

RESULTS

All animals survived IRE ablation, and no cardiac adverse effects were noted. Sixty minutes after IRE, a hypodense lesion on computed tomography imaging indicated the ablation zone. None of the animals developed clinical signs of acute pancreatitis. Only small amounts of ascites fluid, with a transient increase in amylase and lipase levels, were observed, indicating that no pancreatic fistula occurred.

CONCLUSIONS

This porcine model shows that IRE is feasible and safe in the pancreatic parenchyma. Computed tomography imaging reveals significant changes at 60 minutes after IRE and therefore might serve as an early indicator of therapeutic success. Clinical studies are needed to evaluate the efficacy of IRE in pancreatic cancer.

Safety and feasibility of Irreversible Electroporation (IRE) in patients with locally advanced pancreatic cancer: results of a prospective study

PURPOSE

To evaluate the safety of the NanoKnife Low Energy Direct Current (LEDC) System (Irreversible Electroporation, IRE) in order to treat patients with unresectable pancreatic adenocarcinoma.

METHODS

Prospective, nonrandomized, single-center clinical evaluation of ten patients with a cytohystological diagnosis of unresectable locally advanced pancreatic cancer (LAPC) that was no further responsive to standard treatments. The primary outcome was the rate of procedure-related abdominal complications. The secondary endpoints included the evaluation of the short-term efficacy of IRE through the evaluation of tumor reduction at imaging and biological tumor response as shown by CA 19-9, clinical assessments and patient quality of life.

RESULTS

Ten patients (5 males, 5 females) were enrolled, with a median age of 66 and median tumor size of 30 mm. All patients were treated successfully with a median procedure time of 79.5 min. Two procedure-related complications were described in one patient (10%): a pancreatic abscess with a pancreoduodenal fistula. Three patients had early progression of disease: one patient developed pulmonary metastases 30 days post-IRE and two patients had liver metastases 60 days after the procedure. We registered an overall survival of 7.5 months (range: 2.9-15.9).

CONCLUSIONS

IRE is a safe procedure in patients with LAPC and may represent a new technological option in the treatment and multimodality management of this disease.

Systematic review of irreversible electroporation in the treatment of advanced pancreatic cancer

BACKGROUND

Irreversible electroporation (IRE) is a novel procedure to combat pancreatic cancer, whereby high voltage pulses are delivered, resulting in cell death. This represents an ideal alternative to other thermal treatment modalities, as there is no overriding heat effect, therefore reducing the risk of injury to vessels and ducts.

METHODS

Multiple databases were searched to January 2014. Primary outcome measures were survival and associated morbidity. 41 articles were initially identified; of these 4 studies met the inclusion criteria, yielding 74 patients in total.

RESULTS

94.5% of patients had locally advanced tumours, the remainder had metastatic disease. Treated tumour size ranged from 1 to 7 cm. IRE approach included open (70.3%), laparoscopic (2.7%) and percutaneous (27%; ultrasound-guided 30%, CT-guided 70%) Morbidity ranged from 0 to 33%; due to the high number of simultaneous procedures performed (resection/bypass) it was difficult to ascertain IRE-related complications. However no significant bleeding occurred when IRE-alone was performed. Survival statistics suggest a prognostic benefit. Reported survival included: 6 month survival of 40% (n = 5) and 70% (n = 14); PFS and OS 14 and 20 months respectively (n = 54). Results of most interest showed a significant survival benefit in matched IRE vs non-IRE groups (PFS 14 vs 6 mths; p = 0.01, OS 20 vs 11 mths; p = 0.03).

CONCLUSION

Initial evidence suggests IRE incurs a prognostic benefit with minimal morbidity. More high quality research is required to determine the role IRE may play in the multi-modal management of pancreatic cancers.

Feasibility and Safety of Intraoperative Electrochemotherapy in Locally Advanced Pancreatic Tumor: A Preliminary Experience

Electrochemotherapy is an effective treatment for various cutaneous tumors and could be translated into treatment of deep-seated tumors. With this aim, a prospective clinical phase I/II study was conducted to evaluate the feasibility and safety of intraoperative Electrochemotherapy (ECT) in locally advanced pancreatic adenocarcinoma: the preliminary results are reported in this study. The secondary endpoint was to assess treatment response in terms of morphological and functional criteria based on Magnetic Resonance Imaging. Eleven consecutive patients were enrolled in a clinical phase I/II study approved by the Ethics Committee of the National Cancer Institute G. Pascale Foundation - IRCCS of Naples. Electrochemotherapy with bleomycin was performed during open surgery. All patients underwent MR and CT scan, before and after ECT treatment, using morphological and functional imaging. RECIST criteria were used to evaluate ECT response on CT and MR images. Functional parameters were also used to evaluate ECT response on MR images. No acute (intraoperative) and/or postoperative serious adverse events related to electrochemotherapy were observed; no clinically significant electrocardiographic, hemodynamic, or serum biologic changes were noted. No clinically relevant elevation of amylase or lipase levels was observed and no bleeding or damage to surrounding viscera occurred. Electrochemotherapy of locally advanced pancreatic adenocarcinoma proved to be a feasible and safe treatment modality. Dynamic and diffusion MR imaging is more suitable to assess ECT treatment response than CT imaging and morphological MR alone, after one month of treatment.

An "Off-the-Shelf" System for Intraprocedural Electrical Current Evaluation and Monitoring of Irreversible Electroporation Therapy

INTRODUCTION

Irreversible electroporation (IRE) ablation uses a series of brief electric pulses to create nanoscale defects in cell membranes, killing the cells. It has shown promise in numerous soft-tissue tumor applications. Larger voltages between electrodes will increase ablation volume, but exceeding electrical limits may risk damage to the patient, cause ineffective therapy delivery, or require generator restart. Monitoring electrical current for these conditions in real-time enables managing these risks. This capacity is not presently available in clinical IRE generators.

METHODS

We describe a system using a Tektronix TCP305 AC/DC Current Probe connected to a TCPA300 AC/DC Current Probe Amplifier, which is read on a computer using a Protek DSO-2090 USB computer-interfacing oscilloscope. Accuracy of the system was tested with a resistor circuit and by comparing measured currents with final outputs from the NanoKnife clinical electroporation pulse generator.

RESULTS

Accuracy of measured currents was 1.64 ± 2.4 % relative to calculations for the resistor circuit and averaged 0.371 ± 0.977 % deviation from the NanoKnife. During clinical pulse delivery, the system offers real-time evaluation of IRE procedure progress and enables a number of methods for identifying approaching issues from electrical behavior of therapy delivery, facilitating protocol changes before encountering therapy delivery issues.

CONCLUSIONS

This system can monitor electrical currents in real-time without altering the electric pulses or modifying the pulse generator. This facilitates delivering electric pulse protocols that remain within the optimal range of electrical currents-sufficient strength for clinically relevant ablation volumes, without the risk of exceeding safe electric currents or causing inadequate ablation.

Evaluation of thermal injury to liver, pancreas and kidney during irreversible electroporation in an in vivo experimental model

BACKGROUND

Irreversible electroporation (IRE) is a new technique for tumour cell ablation that is reported to involve non-thermal-based energy using high voltage at short microsecond pulse lengths. In vivo assessment of the thermal energy generated during IRE has not been performed. Thermal injury can be predicted using a critical temperature model. The aim of this study was to assess the potential for thermal injury during IRE in an in vivo porcine model.

METHODS

In vivo continuous temperature assessments of 86 different IRE procedures were performed on porcine liver, pancreas, kidney and retroperitoneal tissue. Tissue temperature was measured continuously throughout IRE by means of two thermocouples placed at set distances (0·5 cm or less, and 1 cm) from the IRE probes within the treatment field. Thermal injury was defined as a tissue temperature of 54°C lasting at least 10 s. Tissue type, pulse length, probe exposure length, number of probes and retreatment were evaluated for associations with thermal injury. In addition, IRE ablation was performed with metal clips or metal stents within the ablation field to determine their effect on thermal injury.

RESULTS

An increase in tissue temperature above the animals' baseline temperature (median 36·0°C) was generated during IRE in all tissues studied, with the greatest increase found at the thermocouple placed within 0·5 cm in all instances. On univariable and multivariable analysis, ablation in kidney tissue (maximum temperature 62·8°C), ablation with a pulse length setting of 100 µs (maximum 54·7°C), probe exposure of at least 3·0 cm (maximum 52·0°C) and ablation with metal within the ablation field (maximum 65·3°C) were all associated with a significant risk of thermal injury.

CONCLUSION

IRE can generate thermal energy, and even thermal injury, based on tissue type, probe exposure lengths, pulse lengths and proximity to metal. Awareness of probe placement regarding proximity to critical structures as well as probe exposure length and pulse length are necessary to ensure safety and prevent thermal injury. A probe exposure of 2·5 cm or less for liver IRE, and 1·5 cm or less for pancreas, with maximum pulse length of 90 µs will result in safe and non-thermal energy delivery with spacing of 1·5-2·3 cm between probe pairs.

Intraoperative electrochemotherapy of colorectal liver metastases

BACKGROUND AND OBJECTIVES

Electrochemotherapy is effective in treatment of various cutaneous tumors and could be translated into treatment of deep-seated tumors. With this aim a prospective pilot study was conducted to evaluate feasibility, safety, and efficacy of intraoperative electrochemotherapy in the treatment of colorectal liver metastases.

METHODS

Electrochemotherapy with bleomycin was performed during open surgery, by insertion of long needle electrodes into and around the tumor according to the individualized pretreatment plan.

RESULTS

A 29 metastases in 16 patients were treated in 16 electrochemotherapy sessions. No immediate (intraoperative) and/or postoperative serious adverse events related to electrochemotherapy were observed. Radiological evaluation of all the treated metastases showed 85% complete responses and 15% partial responses. In a group of seven patients that underwent a second operation at 6-12 weeks after the first one, during which electrochemotherapy was performed, the histology of resected metastases treated by electrochemotherapy showed less viable tissue (P = 0.001) compared to non-treated ones.

CONCLUSIONS

Electrochemotherapy of colorectal liver metastases proved to be feasible, safe, and efficient treatment modality, providing its specific place in difficult to treat metastases, located in the vicinity of major hepatic vessels, not amenable to surgery or radiofrequency ablation.

Microwave ablation of pancreatic head cancer: safety and efficacy

PURPOSE

To evaluate the safety and efficacy of percutaneous microwave (MW) ablation treatment in locally advanced, nonresectable, nonmetastatic pancreatic head cancer.

MATERIALS AND METHODS

Ten patients with pancreatic head cancer treated with percutaneous (n = 5) or laparotomic (n = 5) MW ablation were retrospectively reviewed. The MW generator used (45 W at 915 MHz) was connected by coaxial cable to 14-gauge straight MW antennas with a 3.7- or 2-cm radiating section. One or two antennae were used, with an ablation time of 10 minutes. Ultrasonographic (US) and combined US/cone-beam computed tomographic (CT) guidance were used in five patients each. Follow-up was performed by CT after 1, 3, 6, and, when possible, 12 months. Tumor response was assessed per Response Evaluation Criteria In Solid Tumors (version 1.1) and Choi criteria. The feasibility, safety, and major and minor complications associated with quality of life (QOL) were recorded prospectively.

RESULTS

The procedure was feasible in all patients (100%). One late major complication was observed in one patient, and no visceral injury was detected. No patient had further surgery, and all minor complications resolved during the hospital stay. An improvement in QOL was observed in all patients despite a tendency to return to preoperative levels in the months following the procedure, without the influence of minor complications. No repeat treatment was performed.

CONCLUSIONS

Despite the small number of patients, the present results can be considered encouraging, showing that MW ablation is a feasible approach in the palliative treatment of pancreatic tumors.

Irreversible electroporation for nonthermal tumor ablation in the clinical setting: a systematic review of safety and efficacy

PURPOSE

To provide an overview of current clinical results of irreversible electroporation (IRE), a novel, nonthermal tumor ablation technique that uses electric pulses to induce cell death, while preserving structural integrity of bile ducts and vessels.

METHODS

All in-human literature on IRE reporting safety or efficacy or both was included. All adverse events were recorded. Tumor response on follow-up imaging from 3 months onward was evaluated.

RESULTS

In 16 studies, 221 patients had 325 tumors treated in liver (n = 129), pancreas (n = 69), kidney (n = 14), lung (n = 6), lesser pelvis (n = 1), and lymph node (n = 2). No major adverse events during IRE were reported. IRE caused only minor complications in the liver; however, three major complications were reported in the pancreas (bile leak [n = 2], portal vein thrombosis [n = 1]). Complete response at 3 months was 67%-100% for hepatic tumors (93%-100% for tumors o 3 cm). Pancreatic IRE combined with surgery led to prolonged survival compared with control patients (20 mo vs 13 mo) and significant pain reduction.

CONCLUSIONS

In cases where other techniques are unsuitable, IRE is a promising modality for the ablation of tumors near bile ducts and blood vessels. This articles gives an extensive overview of the available evidence, which is limited in terms of quality and quantity. With the limitations of the evidence in mind, IRE of central liver tumors seems relatively safe without major complications, whereas complications after pancreatic IRE appear more severe. The available limited results for tumor control are generally good. Overall, the future of IRE for difficult-to-reach tumors appears promising.

Electrochemotherapy: from the drawing board into medical practice

Electrochemotherapy is a local treatment of cancer employing electric pulses to improve transmembrane transfer of cytotoxic drugs. In this paper we discuss electrochemotherapy from the perspective of biomedical engineering and review the steps needed to move such a treatment from initial prototypes into clinical practice. In the paper also basic theory of electrochemotherapy and preclinical studies in vitro and in vivo are briefly reviewed. Following this we present a short review of recent clinical publications and discuss implementation of electrochemotherapy into standard of care for treatment of skin tumors, and use of electrochemotherapy for other targets such as head and neck cancer, deep-seated tumors in the liver and intestinal tract, and brain metastases. Electrodes used in these specific cases are presented with their typical voltage amplitudes used in electrochemotherapy. Finally, key points on what should be investigated in the future are presented and discussed.

Percutaneous ablation of peribiliary tumors with irreversible electroporation

PURPOSE

To assess biliary complications after irreversible electroporation (IRE) ablation of hepatic tumors located < 1 cm from major bile ducts.

MATERIALS AND METHODS

A retrospective review was conducted of all percutaneous IRE ablations of hepatic tumors within 1 cm of the common, left, or right hepatic ducts at a single institution from January 2011 to September 2012. Computed tomography imaging performed before and after treatment was examined for evidence of bile duct dilatation, stricture, or leakage. Serum bilirubin and alkaline phosphatase levels were analyzed for evidence of biliary injury.

RESULTS

There were 22 hepatic metastases in 11 patients with at least one tumor within 1 cm of the common, left, or right hepatic duct that were treated with IRE ablations in 15 sessions. Median tumor size treated was 3.0 cm (mean, 2.8 cm ± 1.2, range, 1.0-4.7 cm). Laboratory values obtained after IRE were considered abnormal after four treatment sessions in three patients (bilirubin, 2.6-17.6 mg/dL; alkaline phosphatase, 130-1,035 U/L); these abnormal values were transient in two sessions. Two patients had prolonged elevation of values, and one required stent placement; both of these conditions appeared to be secondary to tumor progression rather than bile duct injury.

CONCLUSIONS

This clinical experience suggests that IRE may be a treatment option for centrally located liver tumors with margins adjacent to major bile ducts where thermal ablation techniques are contraindicated. Further studies with extended follow-up periods are necessary to establish the safety profile of IRE in this setting.

Interventional radiology and the pancreatic cancer patient

Patients with pancreatic cancer have a dismal prognosis. This article reviews the role that interventional radiology can play in managing postoperative complications and in patient palliation, particularly with an obstructed biliary system. In addition, options for cytoreduction are discussed, including chemoembolization, radioembolization, and thermal ablation. The final option reviewed is irreversible electroporation, which is being explored as a technique to allow patients with locally advanced pancreatic cancer to be converted to surgical candidates.

Percutaneous irreversible electroporation for downstaging and control of unresectable pancreatic adenocarcinoma

PURPOSE

Treatment of unresectable locally advanced pancreatic cancer (LAPC) usually includes chemotherapy and/or radiation therapy in an attempt to downstage these tumors to the extent of resectability, but outcomes remain poor. Irreversible electroporation (IRE) is an ablative modality that may be useful in this population. The aim of this study was to evaluate the safety of percutaneous IRE in patients with pancreatic adenocarcinoma.

MATERIALS AND METHODS

IRE was performed in patients with pancreatic cancer whose tumors remained unresectable after, or who were intolerant of, standard therapy. The procedures were all done percutaneously under general anesthesia. Patients were then followed for adverse events, tumor response, and survival.

RESULTS

Fifteen IRE procedures were performed in 14 patients (one was treated twice). Three patients had metastatic disease and 11 had LAPC. All patients had received chemotherapy previously, and 11 had received radiation. The median tumor size was 3.3 cm (range, 2.5-7 cm). Immediate and 24-hour postprocedural scans demonstrated patent vasculature in the treatment zone in all patients. Two patients underwent surgery 4 and 5 months after IRE, respectively. Both had margin-negative resections, and one had a pathologic complete response; both remain disease-free after 11 and 14 months, respectively. Complications included spontaneous pneumothorax during anesthesia (n = 1) and pancreatitis (n = 1), and both patients recovered completely. There were no deaths directly related to the procedure. All three patients with metastatic disease at IRE died from progression of their disease.

CONCLUSIONS

Percutaneous IRE for pancreatic adenocarcinoma is feasible and safe. A prospective trial is being planned.

A three-dimensional in vitro tumor platform for modeling therapeutic irreversible electroporation

Irreversible electroporation (IRE) is emerging as a powerful tool for tumor ablation that utilizes pulsed electric fields to destabilize the plasma membrane of cancer cells past the point of recovery. The ablated region is dictated primarily by the electric field distribution in the tissue, which forms the basis of current treatment planning algorithms. To generate data for refinement of these algorithms, there is a need to develop a physiologically accurate and reproducible platform on which to study IRE in vitro. Here, IRE was performed on a 3D in vitro tumor model consisting of cancer cells cultured within dense collagen I hydrogels, which have been shown to acquire phenotypes and respond to therapeutic stimuli in a manner analogous to that observed in in vivo pathological systems. Electrical and thermal fluctuations were monitored during treatment, and this information was incorporated into a numerical model for predicting the electric field distribution in the tumors. When correlated with Live/Dead staining of the tumors, an electric field threshold for cell death (500 V/cm) comparable to values reported in vivo was generated. In addition, submillimeter resolution was observed at the boundary between the treated and untreated regions, which is characteristic of in vivo IRE. Overall, these results illustrate the advantages of using 3D cancer cell culture models to improve IRE-treatment planning and facilitate widespread clinical use of the technology.

Efficient electroporation of liposomes doped with pore stabilizing nisin

CONTEXT

Liposomes have a long history as passive and active drug carriers. Recently, a few methods have been realized to control the release from liposomes, including heating, ultrasound and laser.

OBJECTIVE

We report on a new approach to drive release from liposomes using electric fields.

MATERIALS AND METHODS

Liposomes were manufactured containing a high concentration of (quenched) 5-6 carboxyfluorescein dye. Nisin, a well-known amphiphilic peptide lantibiotic that works by stabilizing pores formed in cell membranes, was mixed in solution inside or outside the liposomes. The liposomes were then electroporated using a range of voltages, and assayed for increases in fluorescence due to release of dye. Release was measured against positive and negative controls, with positive control release driven by a strong detergent.

RESULTS

Our results demonstrate that the addition of nisin significantly reduces the electric field required to release the contents of liposomes, from 2000 V/m to approximately 200 V/m. This result proves that, in principle, electroporation (EP) of liposomes doped with small amounts of amphiphilic pore stabilizing peptides may be a practical means to drive release of liposomal contents in vivo.

CONCLUSION

Drug delivery from liposomes doped with amphiphilic peptides using EP is feasible. This technique could be developed into a potent adjuvant to tumor ablation using irreversible EP.

Safety and early efficacy of irreversible electroporation for hepatic tumors in proximity to vital structures

INTRODUCTION

Irreversible electroporation (IRE) has shown promise for ablation of lesions in proximity to vital structures in the preclinical setting. This study aims to evaluate the safety and efficacy of IRE for hepatic tumors in the clinical setting.

METHODS

An IRB approved prospective registry of patients undergoing IRE for hepatic tumors over a 2-year period. Factors analyzed included patient and tumor characteristics, treatment related complications, and local recurrence free survival (LRFS) for ablated lesions. LRFS was calculated according to Kaplan-Meier, with secondary analyses stratified by procedural approach (laparotomy, laparoscopy, and percutaneous) and tumor histology.

RESULTS

There were 44 patients undergoing 48 total IRE procedures, 20 colorectal mets, 14 hepatocellular, and 10 other metastatsis. Initial success was achieved in 46 (100%) treatments. Five patients had 9 adverse events, with all complications resolving within 30 days. LRFS at 3, 6, and 12 months was 97.4%, 94.6%, and 59.5%. There was a trend toward higher recurrence rates for tumors over 4 cm (HR 3.236, 95% CI: 0.585-17.891; P = 0.178).

CONCLUSIONS

IRE appears to be a safe treatment for hepatic tumors in proximity to vital structures. Further prospective evaluation is needed to determine the optimal effectiveness of IRE in relation to size and technique for IRE of the liver.

Nonthermal irreversible electroporation: fundamentals, applications, and challenges

Tissue ablation is an essential procedure for the treatment of many diseases. In the last decade, a nonthermal tissue ablation using intensive pulsed electric fields, called nonthermal irreversible electroporation (NTIRE), has rapidly emerged. The exact mechanisms responsible for cell death by NTIRE, however, are currently unknown. Nevertheless, the technique's remarkable ability to ablate tissue in the proximity of larger blood vessels, to preserve tissue architecture, short procedure duration, and shortened postoperative recovery period rapidly moved NTIRE from bench to bed side. This work provides an overview on the development of NTIRE, its current state-of-the-art, challenges, and future needs.